This application is a National Stage Application of PCT/JP96/01333, filed May 20, 1996.
1. Field of the Invention
The present invention relates to a magnetic particle control method and apparatus using a sample distributor, which separates magnetic particles combined with a target substance from a liquid by magnetic force or suspends them in a liquid.
2. Description of Related Art
In recent years, a method has come to be used in a biotechnology field, which separates only a target substance from a liquid by using magnetic particles. This method has found a wide range of applications such as immunoassay, DNA hybridization, PCR, separation of cells, separation or washing of protein.
Separation of an objective substance by using magnetic particles has conventionally been achieved in the following manner. A piston in a syringe-like cylinder is manually lifted to draw a liquid containing magnetic particles into the cylinder. During this suction process, the magnetic particles in the liquid are attracted to magnets arranged on the outer side of the cylinder or of a container of the distribution tip portion (liquid reservoir portion). Then, the piston is lowered to discharge the liquid, leaving the magnetic particles adhering to the inner surface of the distribution tip portion. In this way, the magnetic particles are separated.
Then, with the magnetic particles separated from the liquid, the piston is raised again to draw another liquid into the tip thereby resetting the magnetic action on the magnetic particles. As a result, the magnetic particles are suspended in the liquid. In this condition, the piston is lowered to discharge the magnetic article-suspended liquid from the tip.
With such a manual separation or suspension method, it is practically impossible to enhance precision and sensitivity of the processes, such as attaching and detaching the pipette tip, putting the magnets toward and away from the pipette tip, controlling the relative positions of the pipette tip and the magnets, and separation, agitation and cleaning of magnetic particles. Hence, a highly automated sample distribution system is essential for controlling the magnetic particles systematically with high precision.
To perform a highly sensitive control by applying a magnetic field to the magnetic particles requires a complex and delicate setting of magnetic field, cylinder shape and operating conditions.
The present invention has been accomplished under these circumstances.
A primary objective of the present invention is to provide a control method and apparatus for controlling magnetic particles by an improved sample distributor.
A second objective of this invention is to provide a control method and apparatus for controlling magnetic particles by a sample distributor, in which not only separation and movement but also agitation, cleaning, re-suspending and mixing of magnetic particles are made possible with a highly automated sample distributor by performing a variety of liquid suction and discharge operations according to various settings and their combinations, such as speed, quantity and number of repetitions, to realize reliable control in highly precise amounts of liquids.
A third objective is to provide a control method and apparatus for controlling magnetic particles by a sample distributor, which applies a magnetic field to magnetic particles highly responsively to enable precise and complex control.
A fourth objective is to provide a control method and apparatus for controlling magnetic particles by a sample distributor, which enables complex and reliable control by simple operations.
A fifth objective is to provide a control method and apparatus for controlling magnetic particles by a sample distributor, which can automatically set and specify the most efficient and fast processing.
A sixth objective is to provide a control method and apparatus for controlling magnetic particles by a sample distributor, which can perform safe, uncontaminated, reliable processing.
A seventh objective is to provide a control method and apparatus for controlling magnetic particles by a sample distributor, which can be realized with a simple and inexpensive construction.
An eighth objective is to provide a control method and apparatus for controlling magnetic particles by a sample distributor, which can specify a variety of operations by setting various processing patterns and is therefore versatile and applicable to a wide range of applications